Generating multiple pulse trains from a micro-comb laser

Abstract

A method and system, the method including: obtaining a plurality of coherent subcarriers, each of the plurality of coherent subcarriers having a subcarrier frequency from a set of subcarrier frequencies, the set of subcarrier frequencies being equally spaced; filtering a first group of subcarriers having consecutive frequencies from the set of subcarrier frequencies, thereby obtaining a first sequence of equally spaced pulses in the time domain; and filtering a second group of subcarriers having consecutive frequencies from the set of carrier frequencies, thereby obtaining a second sequence of equally spaced pulses in the time domain, the second group being different from the first group, thereby obtaining at least two sequences of equally spaced time-domain pulses having different wavelengths, the at least two sequences of equally spaced time-domain pulses having different wavelengths.

Description

[Technical Field]

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 484,226, entitled "Generating a Plurality of Pulse Trains from a Micro Comb Laser," filed February 10, 2023, the entire contents of which are hereby incorporated by reference without denial.

[0002] The present disclosure relates generally to the use of comb laser sources, and more particularly to the use of comb laser sources to generate and use multiple equally spaced time-domain pulse trains. [Background technology]

[0003] A frequency comb is a laser source whose spectrum consists of a series of discrete, equally spaced frequency lines.

[0004] The frequency domain representation of the complete frequency comb is f n =f0+nf r where n is an integer and f r is the comb tooth spacing equal to the repetition rate of the mode-locked laser or alternatively the modulation frequency, and f is r is a lower carrier offset frequency.

[0005] Comb lasers can be implemented in various ways, two of which include semiconductor mode-locked lasers made of semiconductors with saturable absorption regions, and micro-ring comb lasers, which use the nonlinear effect of a micro-ring. These comb lasers are hereafter collectively referred to as micro-comb lasers.

[0006] Referring now to FIG. 1, there is shown a schematic diagram of the output of a micro-comb laser, which includes a sequence of equally spaced coherent optical subcarriers, as used in some exemplary embodiments of the present disclosure.

[0007] The output includes multiple subcarriers, such as subcarriers 104, 108, 112, and 116, each having a subcarrier frequency, where the subcarrier frequencies are equally spaced, i.e., the frequency spacing between any two consecutive subcarriers is constant. In the example of Figure 1, the frequencies are equally spaced over a range from about 1530 to about 1630. Figure 1 also shows noise 120 with an amplitude significantly lower than the amplitude of the primary subcarrier.

[0008] Although Figure 1 shows a wavelength range of about 1530 nm to about 1630 nm, this is merely an example, and other wavelength ranges may be generated by appropriate design of the micro-ring and distributed feedback (DFB) laser source. For example, an O-band DFB laser source may generate a wavelength range of 1270 nm to 1330 nm.

[0009] Referring now to FIG. 2, there is shown a schematic diagram of an exemplary micro ring comb laser system as used in some exemplary embodiments of the present disclosure.

[0010] The system comprises a DFB laser source 200 that emits light 204 at a predetermined frequency. The light is coupled into an integrated photonic circuit through an optical coupler and then transported via a waveguide 216, which is preferably an ultra-low loss waveguide.

[0011] The light is coupled into a micro-ring resonator (MRR), generally referenced 206. The MRR 206 comprises a micro-resonator ring 208 and a thermal heater ring 212 for heating and thereby fine-tuning the resonant frequency of the micro-resonator ring 208, and therefore tuning the resonant frequency to the frequency of the light source (200). The ring 208 resonates at wavelengths where its perimeter divided by the wavelength is an integer, i.e., (2*π*r) / λ=N, where r is the ring radius and λ is the wavelength of the light 204. Therefore, for the ring to resonate at a certain wavelength, its perimeter needs to be adjusted to correspond to the wavelength, and this adjustment may be accomplished by the thermal heater ring 212.

[0012] Thus, output light 216 contains subcarriers at equally spaced frequencies, as shown in FIG.

[0013] Comb lasers are used in various applications in the communications field as sources that generate multiple wavelengths. In some exemplary uses, the wavelengths may be separated and one or more of them may be modulated to allow large amounts of data to be transmitted at high speeds. Summary of the Invention [Means for solving the problem]

[0014] One exemplary embodiment of the disclosed subject matter is a method including: obtaining a plurality of coherent subcarriers, each having a subcarrier frequency from a set of equally spaced subcarrier frequencies; filtering a first group of subcarriers having consecutive frequencies from the set of subcarrier frequencies, thereby obtaining a first sequence of equally spaced pulses in the time domain; and filtering a second group of subcarriers having consecutive frequencies from the set of subcarrier frequencies, thereby obtaining a second sequence of equally spaced pulses in the time domain, the second group different from the first group, thereby obtaining at least two sequences of equally spaced time-domain pulses, the at least two sequences of equally spaced time-domain pulses having different wavelengths, wherein a first wavelength of the first sequence of equally spaced time-domain pulses optionally depends on a center frequency of the first group of subcarriers, and a second wavelength of the second sequence of equally spaced time-domain pulses optionally depends on a center frequency of the second group of subcarriers. In the method, the first group of subcarriers and the second group of subcarriers optionally do not have any subcarriers in common, wherein a smaller number of subcarriers in the first group of subcarriers optionally provide wider pulses in the first sequence of equally spaced time-domain pulses, a larger number of subcarriers in the first group of consecutive lightwaves optionally provide narrower pulses in the first sequence of equally spaced time-domain pulses, a smaller number of subcarriers in the second group of consecutive lightwaves optionally provide wider pulses in the second sequence of equally spaced time-domain pulses, and a larger number of subcarriers in the second group of consecutive lightwaves optionally provide narrower pulses in the second sequence of equally spaced time-domain pulses.The method may further include providing the first sequence of equally-spaced time-domain pulses to a first chirped Bragg grating filter to obtain a reshaped first sequence of equally-spaced time-domain pulses or providing the second sequence of equally-spaced time-domain pulses to a second chirped Bragg grating filter to obtain a second sequence of reshaped equally-spaced time-domain pulses. The method may further include transmitting the modulated first sequence of equally-spaced time-domain pulses or the reshaped second sequence of equally-spaced time-domain pulses to a semiconductor optical amplifier (SOA) for amplification. The method may further include modulating the first sequence of equally-spaced time-domain pulses or the reshaped second sequence of equally-spaced time-domain pulses. The method may further include transmitting the modulated first sequence of equally-spaced time-domain pulses or the reshaped second sequence of equally-spaced time-domain pulses to the SOA for amplification. The method may further include using the first sequence of equally-spaced time-domain pulses or the second sequence of equally-spaced time-domain pulses as an optical clock. The method may further include providing the first sequence of equally-spaced time-domain pulses to a first variable optical attenuator (VOA) to obtain a first high-rate sequence of single photons at the wavelength of the first sequence of equally-spaced time-domain pulses or providing the second sequence of equally-spaced time-domain pulses to a second VOA to obtain a second high-rate sequence of single photons at the wavelength of the second sequence of equally-spaced time-domain pulses. The method may further include using the first high-rate sequence of single photons or the second high-rate sequence of single photons as a quantum bit source. In the method, each of the first group of consecutive lightwaves and the second group of consecutive lightwaves optionally includes at least eight lightwaves.

[0015] Another illustrative embodiment of the disclosed subject matter includes a laser source for emitting a light wave; an apparatus for generating a plurality of coherent subcarriers from the light wave, each of the plurality of coherent subcarriers having a subcarrier frequency from a set of carrier frequencies, the set of subcarrier frequencies being equally spaced; at least a first filter for filtering a first group of subcarriers having consecutive frequencies from the set of subcarrier frequencies, thereby obtaining a first sequence of equally spaced pulses in the time domain; and at least a second filter for filtering a second group of subcarriers having consecutive frequencies from the set of subcarrier frequencies, thereby obtaining a first sequence of equally spaced pulses in the time domain. a semiconductor optical amplifier for amplifying light waves to obtain at least one optical data signal; a variable optical attenuator for converting the first sequence of equally spaced pulses or the second sequence of equally spaced pulses into a single-photon sequence; and a semiconductor optical amplifier for amplifying light waves, thereby generating an optical clock signal; and an arrayed-waveguide grating for multiplexing the at least one optical data signal, single-photon sequence, or optical clock signal into the integrated optical beam. The system may further include a receiving system including an arrayed-waveguide grating for demultiplexing the integrated optical beam, a photodetector for receiving the demultiplexed pulse train from the integrated optical beam, a transimpedance amplifier for obtaining electronic data or clock pulses, and a single-photon avalanche photodetector for obtaining the single-photon sequence.

[0016] The subject matter of the present disclosure will be more fully understood and appreciated from the following detailed description taken in conjunction with the drawings, in which corresponding or like numerals or letters indicate corresponding or like components. Unless otherwise indicated, the drawings provide illustrative examples or aspects of the present disclosure and do not limit the scope of the disclosure. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a schematic diagram of the output of a micro-comb laser containing a sequence of equally spaced optical subcarriers, as used in some embodiments of the present disclosure. [Figure 2] FIG. 1 is a schematic diagram of an example micro ring comb laser system as used in some example embodiments of the present disclosure. [Figure 3A] FIG. 1 illustrates a selected group of contiguous subcarriers, according to some example embodiments of the present disclosure. [Figure 3B] FIG. 1 illustrates a selected group of contiguous subcarriers, according to some example embodiments of the present disclosure. [Figure 4A] FIG. 3B illustrates a pulse train resulting from the subcarrier group of FIG. 3A, in accordance with some exemplary embodiments of the present disclosure. [Figure 4B] FIG. 3C illustrates a pulse train resulting from the subcarrier group of FIG. 3B, in accordance with some exemplary embodiments of the present disclosure. [Figure 5A] FIG. 10 illustrates pulse trains obtained from groups of subcarriers with different numbers of harmonics. [Figure 5B] FIG. 10 illustrates pulse trains obtained from groups of subcarriers with different numbers of harmonics. [Figure 5C] FIG. 10 illustrates pulse trains obtained from groups of subcarriers with different numbers of harmonics. [Figure 5D] FIG. 10 illustrates pulse trains obtained from groups of subcarriers with different numbers of harmonics. [Figure 5E]FIG. 10 illustrates pulse trains obtained from groups of subcarriers with different numbers of harmonics. [Figure 6] 1 is a schematic diagram of a sliced ​​micro ring comb laser, according to some example embodiments of the present disclosure. [Figure 7] FIG. 1 is a schematic block diagram of a system for using multiple equally spaced pulse trains, according to some example embodiments of the present disclosure. [Figure 8] 1 is a schematic block diagram of a receiving system, according to some example embodiments of the present disclosure. [Figure 9] 1 is a flowchart of a method for generating and using a pulse train from a micro-comb laser, according to some example embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0018] One technical problem addressed by this disclosure is the need to generate multiple precise, high repetition rate, equally spaced pulse trains with different center frequencies.

[0019] Another technical challenge addressed by this disclosure is the need to reliably enable a variety of uses for equally spaced pulse trains, such as data transmission, co-packaged optics, machine learning, spectroscopy, and others, where in some embodiments it can be important that the pulse trains have exactly the same repetition rate.

[0020] One technical solution of the present disclosure relates to obtaining multiple coherent light waves, also called subcarriers, with equally spaced frequencies, such as those emitted from a single micro-comb laser, which can be provided to an optical splitter for dividing the power of the light beam into multiple light beams, each of which can be processed simultaneously and separately.

[0021] A first group of subcarriers, for example, about 8 to about 32 consecutive subcarriers, output by the optical splitter may be filtered from the plurality of subcarriers by, for example, a first optical filter.

[0022] The collection of subcarriers in the first group forms a train of equally spaced pulses in the time domain, the pulses in the train being of a wavelength range having a center wavelength corresponding to a center frequency of the first optical filter.

[0023] A second group of subcarriers, for example, about 8 to about 32 contiguous subcarriers, output by the optical splitter may be filtered from the plurality of subcarriers by, for example, a second optical filter. The first and second groups of subcarriers may have no subcarriers in common.

[0024] The collection of subcarriers in the second group forms a second equally spaced pulse train in the time domain, the pulses in the second pulse train being of a wavelength range having a center wavelength corresponding to the center frequency of the second optical filter.

[0025] Therefore, the center wavelengths of the first and second pulse trains are different, but the pulse rates in the two pulse trains are equal and are determined by the spacing between successive frequencies in the acquired subcarriers, and are therefore equal for the first and second pulse trains.

[0026] Further groups of subcarriers may also be separated from the received set of subcarriers providing pulse trains in the time domain for each different wavelength, since the central wavelength of each of the pulse trains is equal to the central wavelength of the subcarriers in the group that produces the pulse train. The sets of subcarriers providing each of the different wavelengths may also be further separated. It is recognized that all pulse trains are equally spaced and all share the same time difference between successive pulses.

[0027] It is also recognized that the pulse width in each pulse train depends on the number of consecutive subcarriers that form the pulse train in the time domain. Therefore, since short pulses vary faster than longer pulses and are therefore composed of higher frequencies, a wider bandwidth means more frequencies. Therefore, the more subcarriers there are in a group, the narrower each pulse in the pulse train will occupy, and vice versa. Therefore, the number of groups and the number of subcarriers in each group must be selected so that pulses in different pulse trains overlap or do not overlap, as needed. As can be seen in Figure 1, the emitted spectrum of a micro-ring comb laser is not uniform but rather bell-shaped. By selecting an appropriate range from the spectrum, the shape and width of individual pulses in each pulse train can be improved according to requirements while maintaining the same repetition rate. It is recognized that by selecting a limited number of consecutive frequencies, the amplitudes of the selected frequencies are within a relatively narrow range.

[0028] One or more of the pulse trains may be reshaped to obtain a desired pulse shape, for example, using a chirped Bragg grating filter.

[0029] Another technical solution of the present disclosure relates to using one or more of the pulse trains as an optical clock due to their precise high repetition rate.

[0030] Yet another technical solution of the present disclosure relates to using one or more of the pulse trains to carry data by modulating each pulse train according to digital or analog data, thereby generating one or more high repetition rate modulated signals.

[0031] Yet another technical solution of the present disclosure relates to attenuating the pulses of a pulse train to reduce the number of photons in each pulse to a single photon of the same color as the associated pulse, thereby generating a high-rate sequence of single photons at the wavelength of the pulse train, which can be a source for qubit photons.

[0032] Yet another technical solution of the present disclosure relates to time-domain multiplexing of different pulse trains with different center wavelengths, which creates higher data rates and achieves both time and frequency separation of different channels.

[0033] Yet another technical solution of the present disclosure relates to multiplexing one or more modulated pulse trains, all with the same repetition rate, carrying different types of data or data from different sources, and / or an optical clock, and / or one or more single photon sequences. The combining may be performed using an array waveguide grating (AWG). The signals may then be transmitted over a single medium and demultiplexed at the receiver to extract the clock, all data signals, and single photon sequences.

[0034] One technical effect of the present disclosure relates to the use of a micro-comb laser or a semiconductor mode-locked laser (collectively referred to as a micro-comb laser) to generate a sequence of equally spaced time-domain pulses with different center frequencies by using a single micro-ring comb laser, which is easy to generate and has highly accurate time differences.

[0035] Another technical effect of the present disclosure relates to using each pulse train for purposes such as carrying digital data, generating single photon sequences, or simply as an optical clock.

[0036] Yet another technical effect of the present disclosure relates to combining the use of two or more of the above-described pulse trains, thereby transmitting them over a single medium and utilizing their constant repetition rate.

[0037] 3A and 3B, which illustrate selected groups of contiguous subcarriers according to some example embodiments of the present disclosure.

[0038] 3A and 3B show a diagram 300 of wavelengths emitted by a micro-comb laser, such as wavelengths 304, 308, and 312. The frequencies corresponding to the wavelengths are equally spaced, i.e., the difference between any two consecutive frequencies is constant. While all amplitudes are shown to be identical, it is recognized that this is not necessarily the case. For example, taking consecutive groups of subcarriers shown in FIG. 1, the amplitudes are close, but not necessarily identical.

[0039] A first group of consecutive light waves may be selected, such as group 320 containing 16 wavelengths. The wavelengths of the light waves in group 320 range from λ1-Δλ1 to λ1+Δλ1, with an average wavelength of λ1.

[0040] The Fourier transform of a collection of light waves is given by the following equation:

number

[0041] Thus, a sum of equally spaced frequencies in the frequency domain is transformed into a pulse train in the time domain.

[0042] 4A shows a pulse train corresponding to the subcarrier as selected in FIG. 3A, including an exemplary pulse 404, where the time difference between any two consecutive pulses is constant. For example, the time difference between pulses 412 and 416 is equal to the time difference between pulses 404 and 408.

[0043] Similarly, λ M -Δλ M ~λ M +Δλ M 16 wavelengths in the range of λ M A second group of contiguous lightwaves, such as group 324 of Figure 3B, may be selected that includes a center wavelength of , which also provides pulse train 420 as shown in Figure 4B. Note that the first and second groups are different, i.e., do not include the same set of subcarriers.

[0044] Each pulse train has a center frequency, e.g., λ1 for the pulse train of FIG. 4A based on subcarriers in group 320, and λ for the pulse train of FIG. 4B based on subcarriers in group 324. M etc., have a unique wavelength that is the same as the average frequency of the corresponding subcarrier group.

[0045] It is recognized that the time difference between successive pulses in both pulse trains is equal, since this time difference is affected by the spacing between frequencies in the set of subcarriers as output by the micro-comb laser.

[0046] Although Figures 3A, 3B, 4A, and 4B refer to two groups of subcarriers generating two pulse trains, the present disclosure is not limited to two and any number of groups may be generated to form a corresponding number of pulse trains.

[0047] The width of the pulses in each pulse train depends on the number of subcarriers in the selected group, such that groups consisting of a larger number of wavelengths occupy narrower pulse widths and vice versa. In the extreme case, taking one group consisting of all wavelengths results in the narrowest pulse width, but only one pulse train is generated, and in the other extreme, generating a pulse train at any single wavelength results in overlapping wide pulses that are difficult to distinguish.

[0048] In some embodiments, the groups may be selected to be disjoint, i.e., to have no wavelengths in common, which may be beneficial as it allows each pulse to have maximum power without splitting power between pulses belonging to different pulse trains.

[0049] Referring now to FIGS. 5A-5E, the pulse trains obtained when generating a pulse train with a group of subcarriers having different numbers (N) of frequencies starting at zero frequency (DC) and going up to the harmonics are shown. The examples in FIGS. 5A-5E relate to a baseband signal located at zero frequency. However, the same effect can be demonstrated for bandpass signals located around the DFB laser frequency as shown in FIG. 1. Thus, in FIG. 5A, graph 500 shows a null pulse train when no lightwaves are filtered; in FIG. 5B, graph 504 shows a pulse train of a single wavelength; in FIG. 5C, graph 508 shows a pulse train when two wavelengths are filtered; in FIG. 5D, graph 512 shows a pulse train when three wavelengths are filtered; and in FIG. 5E, graph 508 shows a pulse train when eight wavelengths are filtered.

[0050] As the number of subcarriers increases, the highest pulses are seen to become narrower and stronger relative to the side lobes, while maintaining the same repetition rate.

[0051] Referring now to FIG. 6, a schematic diagram of a sliced ​​micro ring comb laser is shown, in accordance with some example embodiments of the present disclosure.

[0052] The DFB laser 200, light 204, MRM 206 comprising microresonator ring 208 and thermal heater ring 212, and output light 216 are as described above in connection with FIG.

[0053] The output light 216, which contains multiple frequencies that fit the diameter of the microresonator ring 208, may be provided to an optical splitter 604 to split the power of the light beam into multiple light beams so that each can be processed separately at the same time.

[0054] Each split light beam passes through a filter, such as tunable optical bandpass filter 1 (608) or tunable optical bandpass filter 2 (620). The filters are grouped 320 with a center frequency of λ1 or λ2. M Each selected group of frequencies as described above forms a pulse train in the time domain, with the pulses in each pulse train having the center frequency of the corresponding group of frequencies.

[0055] Each of the bandpass filters may be a separate element or may be implemented in an integrated photonic platform such as silicon, silicon nitride, or other materials.

[0056] Each pulse train may be passed through a chirped Bragg grating filter, e.g., chirped Bragg grating filter 1 (612) for the first pulse train and chirped Bragg grating filter 2 (624) for the second pulse train.

[0057] A chirped Bragg grating filter may reshape the pulses of the pulse train into a desired shape. Additionally or alternatively, the pulses may be shaped by a high-dispersion fiber.

[0058] In some embodiments, the chirped Bragg grating filter may be implemented using optical fiber or integrated photonics, such as, but not limited to, silicon photonics or silicon nitrite.

[0059] Referring now to FIG. 7, there is shown a schematic block diagram of a system for using multiple equally spaced pulse trains, according to some example embodiments of the present disclosure.

[0060] The system, generally designated 700, receives a train of multiple equally spaced pulses from a micro-comb laser, such as the sliced ​​micro-ring comb laser 600 illustrated in FIG.

[0061] In some embodiments, one or more pulse trains, such as pulse train 701 or pulse train 702, may be encoded with digital or analog information. For example, in the digital case, digital data 1 (704) may be converted from digital data to optical data and used to modulate pulse train 701 by electrical-to-optical (E / O) converter 708 to obtain modulated pulse train 712. Similarly, digital data M (720) may be converted from digital data to optical data and used to modulate pulse train 702 by electrical-to-optical (E / O) converter 724 to obtain modulated pulse train 728. E / O converter 708 or E / O converter 724 may be a Mach-Zehnder modulator, an electroabsorption modulator, a micro-ring modulator, a plasmonic modulator, or any other type. The E / O converter 708 or the E / O converter 724 may be separate devices or may be implemented on any integrated photonic platform to obtain the modulated pulse train 712 or 728.

[0062] Each of the modulated optical beams, such as modulated pulse train 712 or modulated pulse train 728, may be input to a semiconductor optical amplifier (SOA), such as SOA 716 for modulated pulse train 712 or SOA 732 for modulated pulse train 728.

[0063] SOA 716 or SOA 732 may amplify the pulse to a required level.

[0064] Another pulse train, such as pulse train 736, may be provided to a variable optical attenuator (VOA), such as VOA 740, to attenuate the pulses to single photons, thereby generating a single-photon sequence. The sequence may be at a high rate equal to the repetition rate of the pulse train, such as 50 GHz, 100 GHz, or 200 GHz. The required repetition rate may be achieved by appropriate dimensions of the micro-ring. The single-photon sequence may be used as a qubit source.

[0065] Yet another pulse train, such as pulse train 744, may or may not be provided unmodulated to SOA 748, which may amplify the pulses, which may then be used as an optical clock due to the precision of the pulse train.

[0066] Although only two pulse trains modulated with electrical data are shown, it will be appreciated that the system is not limited to two such pulse trains and that any number of pulse trains may be used as determined according to the desired pulse width. It will also be appreciated that multiple single-photon sequences, each having a different wavelength, may be generated, and that multiple electrical clocks may also be implemented, although this may result in unnecessary redundancy.

[0067] Some or all of the above outputs may be fed into an arrayed waveguide grating (AWG) 752 where they may be multiplexed into an output combined light beam 756 .

[0068] Referring now to FIG. 8, there is shown a schematic block diagram of a receiver system for separating and using various components of output light 756, according to some exemplary embodiments of the present disclosure.

[0069] The integrated optical beam 756 output from the transmitter-side AWG 756, which includes one or more streams of data, an optical clock, and / or one or more single-photon sequences that may be used as quantum data and quantum keys, may be received by the receiver-side AWG 800, which may demultiplex it into its various components.

[0070] Thus, AWG 800 may output multiple pulse trains, such as pulse train 808 and pulse train 824. Each pulse train may be provided to a corresponding photodetector, such as photodetector 804 for pulse train 808 or photodetector 820 for pulse train 824.

[0071] The photodetector may output an electrical signal according to the input optical signal, such as electrical signal 808 output by photodetector 804 or electrical signal 824 output by photodetector 820.

[0072] In some embodiments, each electrical signal may be provided to a corresponding trans-impedance amplifier, such as trans-impedance amplifier 812 for electrical signal 808 or trans-impedance amplifier 828 for electrical signal 824, and may output an amplified electrical signal, such as electrical signal 816 or electrical signal 832. The electrical signals and amplified electrical signals may carry data output by the laser source and the sliced ​​micro comb laser, such as sliced ​​micro ring comb laser 600, such as Data 1 (704), Data M (720), or additional data. Thus, electrical signal 816 may carry Data 1 (704), and electrical signal 832 may carry Data M (720).

[0073] In some embodiments, the AWG 800 may also output a single photon sequence 836, which may be provided to a single photon avalanche photodetector (SPAD) 840, which may detect the single photons and output a corresponding electrical signal 844.

[0074] In some embodiments, AWG 800 may also output one or more additional pulse trains that are not encoded with data, such as pulse train 836. A pulse train, such as pulse train 836, may also be fed to a photodetector, such as photodetector 848, to output electrical signal 852, which may be amplified by transimpedance amplifier 856 and output signal 860, which may be used as clock signal 864.

[0075] Therefore, the same micro-ring comb laser may be used to generate various signals, i.e., one or more pulse trains for data transmission, pulse trains for clocking for various purposes, and one or more single-photon sources, thereby creating a multifunctional light source from a single micro-ring comb laser.

[0076] It will be appreciated that since all outputs of AWG 800 are of the same repetition rate, clock 864 may be used to synchronize all other outputs of the system, including Data 1 (704), Data M (720), and electrical signal 844.

[0077] It will be appreciated that the present disclosure is not limited to two data streams, one photon sequence, and one clock signal, but rather any number or combination of the above may be provided.

[0078] Referring now to FIG. 9, there is shown a flowchart of a method for generating and using pulse trains from a micro-comb laser, according to some exemplary embodiments of the present disclosure.

[0079] In step 900, a plurality of light waves of equally spaced frequencies may be received from a source such as a micro-comb laser.

[0080] In step 904, a first successive group of consecutive light waves that, when examined in the time domain, provides a first train of precisely evenly spaced pulses (in time), may be filtered.

[0081] In step 908, a second successive group of consecutive light waves may be filtered that, when examined in the time domain, provides a second train of precisely evenly spaced pulses (in time).

[0082] In step 912, any one or more of the pulse trains may be used as a clock to encode data, generate single photon sequences, or for other uses.

[0083] The present invention may be a system, method, and / or computer program product, which may include a computer-readable storage medium (or media) having computer-readable program instructions for causing a processor to perform aspects of the present invention.

[0084] A computer-readable storage medium may be a tangible device that can hold and store instructions for use by an instruction-execution device, such as, but not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. A non-exhaustive list of more specific examples of computer-readable storage media includes the following: portable computer diskettes, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable compact disc read-only memory (CD-ROM), digital versatile disk (DVD), memory sticks, floppy disks, mechanically encoded devices such as punched cards or raised structures having instructions recorded in grooves, and any suitable combination of the foregoing. Computer-readable storage medium, as used herein, should not be construed as a transitory signal per se, such as a radio wave or other freely propagating electromagnetic wave, an electromagnetic wave propagating through a waveguide or other transmission medium (e.g., a light pulse passing through a fiber optic cable), or an electrical signal transmitted through a wire.

[0085] The computer-readable program instructions described herein can be downloaded from a computer-readable storage medium to an individual computing / processing device or to an external computer or storage device over a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network may include copper transmission cables, fiber optic transmissions, wireless transmissions, routers, firewalls, switches, gateway computers, and / or edge servers. A network adapter card or network interface within each computing / processing device receives the computer-readable program instructions from the network and forwards the computer-readable program instructions for storage on a computer-readable storage medium within the individual computing / processing device.

[0086] The computer-readable program instructions for carrying out the operations of the present invention may be either assembler instructions, instruction-set-architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, state-setting data, or source or object code written in any combination of one or more programming languages, such as "C," C#, C++, Java, Phyton, or Smalltalk. The computer-readable program instructions may execute entirely on the user's computer, partially on the user's computer, as a stand-alone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., through the Internet using an Internet Service Provider). In some embodiments, electronic circuitry including, for example, a programmable logic circuit, a field-programmable gate array (FPGA), or a programmable logic array (PLA) may execute computer-readable program instructions by utilizing state information of the computer-readable program instructions to personalize the electronic circuitry to perform aspects of the invention.

[0087] Aspects of the present invention are described herein with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer-readable program instructions.

[0088] The flowcharts and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of instructions, including one or more executable instructions for implementing a specific logical function. In some alternative implementations, the functions described in the blocks may occur out of the order described in the figures. For example, two blocks shown in succession may, in fact, be executed substantially simultaneously, or the blocks may possibly be executed in the reverse order, depending on the functionality involved. It should also be noted that each block of the block diagrams and / or flowchart diagrams, and combinations of blocks in the block diagrams and / or flowchart diagrams, may be implemented by a dedicated hardware-based system that performs a specified function or operation, or a combination of dedicated hardware and computer instructions.

[0089] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. It will be further understood that as used herein, the terms "comprises" and / or "comprising" specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0090] Corresponding structures, materials, acts, and equivalents of all means- or step-plus-function elements in the following claims are intended to include any structure, material, or act for performing a function in combination with other claimed elements as specifically claimed. The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the invention. The examples were chosen and described in order to best explain the principles and practical applications of the invention and to enable those skilled in the art to understand the invention in various embodiments with various modifications suited to the particular uses contemplated.

Claims

1. obtaining a plurality of coherent subcarriers, each of the plurality of coherent subcarriers having a subcarrier frequency from a set of subcarrier frequencies, the set of subcarrier frequencies being equally spaced; filtering a first group of subcarriers having consecutive frequencies from the set of subcarrier frequencies to obtain a first sequence of equally spaced pulses in the time domain; filtering a second group of subcarriers having consecutive frequencies from the set of carrier frequencies, thereby obtaining a second sequence of equally spaced pulses in the time domain, the second group being different from the first group; Including, A method whereby at least two sequences of equally spaced time-domain pulses are obtained, said at least two sequences of equally spaced time-domain pulses having different wavelengths.

2. 2. The method of claim 1, wherein a first wavelength of the first sequence of equally spaced time-domain pulses depends on a center frequency of the first group of subcarriers, and a second wavelength of the second sequence of equally spaced time-domain pulses depends on a center frequency of the second group of subcarriers.

3. The method of claim 1 , wherein the first group of subcarriers and the second group of subcarriers do not have any common subcarriers.

4. a smaller number of subcarriers in the first group of subcarriers provides wider pulses in the first sequence of equally spaced time-domain pulses; a greater number of subcarriers in the first group of successive lightwaves provides narrower pulses in the first sequence of equally spaced time-domain pulses; a smaller number of subcarriers in the second group of consecutive lightwaves provides wider pulses in the second sequence of equally spaced time-domain pulses; 2. The method of claim 1, wherein a greater number of subcarriers in the second group of continuous lightwaves provides narrower pulse widths in the second sequence of equally spaced time-domain pulses.

5. 10. The method of claim 1, further comprising providing the first sequence of equally spaced time-domain pulses to a first chirped Bragg grating filter to obtain a first sequence of reshaped equally spaced time-domain pulses, or providing the second sequence of equally spaced time-domain pulses to a second chirped Bragg grating filter to obtain a second sequence of reshaped equally spaced time-domain pulses.

6. 6. The method of claim 5, further comprising transmitting the modulated first sequence of reshaped equally-spaced time-domain pulses or the second sequence of reshaped equally-spaced time-domain pulses to a semiconductor optical amplifier (SOA) for amplification.

7. The method of claim 5 , further comprising modulating the first sequence of reshaped equally spaced time-domain pulses or the second sequence of reshaped equally spaced time-domain pulses.

8. 8. The method of claim 7, further comprising transmitting the modulated first sequence of equally spaced time-domain pulses or the second sequence of equally spaced time-domain pulses to an SOA for amplification.

9. The method of claim 1 , further comprising using the first sequence of equally spaced time-domain pulses or the second sequence of equally spaced time-domain pulses as an optical clock.

10. 10. The method of claim 1, further comprising providing the first sequence of equally spaced time-domain pulses to a first variable optical attenuator (VOA) to obtain a first high-rate sequence of single photons at a wavelength of the first sequence of equally spaced time-domain pulses, or providing the second sequence of equally spaced time-domain pulses to a second VOA to obtain a second high-rate sequence of single photons at a wavelength of the second sequence of equally spaced time-domain pulses.

11. 11. The method of claim 10, further comprising using the first high rate sequence of single photons or the second high rate sequence of single photons as a qubit source.

12. The method of claim 1 , wherein the first group of consecutive light waves and the second group of consecutive light waves each include at least eight light waves.

13. a laser light source for emitting light waves; a mechanism for generating a plurality of coherent subcarriers from the lightwave, each of the plurality of coherent subcarriers having a subcarrier frequency from a set of carrier frequencies, the set of subcarrier frequencies being equally spaced; and at least a first filter for filtering a first group of subcarriers having consecutive frequencies from said set of subcarrier frequencies, thereby obtaining a first sequence of equally spaced pulses in the time domain; at least a second filter for filtering a second group of subcarriers having consecutive frequencies from said set of subcarrier frequencies, thereby obtaining a second sequence of equally spaced pulses in the time domain; and an electrical-to-optical converter for converting electrical data into optical data and modulating the first sequence of equally spaced pulses or the second sequence of equally spaced pulses, and a semiconductor optical amplifier for amplifying the light waves to obtain at least one optical data signal; a variable optical attenuator for converting the first sequence of equally spaced pulses or the second sequence of equally spaced pulses into a single photon sequence; and a semiconductor optical amplifier for amplifying said lightwave, thereby generating an optical clock signal; and at least one selected from the group consisting of: an arrayed waveguide grating for multiplexing the at least one optical data signal, the single photon sequence, or the optical clock signal into a unified optical beam; A system comprising:

14. an arrayed waveguide grating for demultiplexing the combined light beam; a photodetector for receiving the demultiplexed pulse train from the integrated light beam and a transimpedance amplifier for obtaining electronic data or clock pulses; Single-photon avalanche photodetector for acquiring single-photon sequences and at least one selected from the group consisting of The system of claim 13 further comprising a receiving system comprising:

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